The invention relates generally to a spiral compressor and more specifically to totally oil free spiral compressor.
When generating compressed air, particularly when generating compressed air totally without oil for rail vehicles, special demands must be made on the compressor technique because of the large amounts of air to be generated and the extremely rough conditions. The full operating ability must always be ensured even under rough environmental conditions (temperature, vibrations, shocks, etc.).
In the field of rail vehicles, oil-free spiral compressors are receiving increased attention, particularly for avoiding the occurrence of an oil-containing condensation and for simplifying the maintenance. Because of the capacity (for example, intake volume flow of approximately 1,600 l/min.) which must be increased considerably in comparison to today's commercially available, oil-free spiral compressors for rail vehicles and the connected high stress to the spiral compressor, such compressors cannot merely be enlarged, particularly in view of the very high axial forces which have the tendency to press apart the spirals of the compressor. In the case of a so-called one-sided spiral arrangement, particularly the support of such axial forces presents problems because very large bearings are required. These problems are becoming more serious because of the required oil-free compression, because of which the friction output of the bearings is very difficult to achieve. For the above-mentioned reasons, compressors with a one-sided spiral arrangement have not been considered to be usable in the rail vehicle field.
Based on the above, it is an object of the invention to further develop a preferably completely oil-free operating spiral compressor with a one-sided spiral arrangement with a large intake volume flow as well as under high compression conditions such that the above-mentioned problems of high axial forces are taken into account. In particular, despite the required volume and compression quantities, an operation of the compressor is to be permitted which is free of high axial forces and thus as free of wear as possible.
The achieving of this object include in the case of a one-sided arrangement of the spirals, specifically of the driving and of the pulled-along spiral, as a result of the pressure chambers fed by pressure pockets of the spiral compressor, a device is created in a very simple manner by means of which the very high axial forces which act upon the bearings can be counteracted. A compensation of these axial forces can therefore be achieved. Despite the high rotational speeds of the two spirals, the function of the pressure chambers is ensured particularly in the case of dry running characteristics of the seals bounding the pressure chambers since only a low relative speed exists between the spirals, thus also in the area of the pressure crown and of the ring wheel which, together with the pressure crown, forms the pressure chambers.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.